The two streams meet at a confluence. It takes many tributary streams to form a river. A river grows larger as it collects water from more tributaries. Streams usually form rivers in the higher elevations of mountains and hills. The areas of depression between hills or mountains are known as valleys.
The world's fastest production single piston engine aircraft produced in Great Britain, deployed from 1945 to 1953. Heavily Modified Sea Fury aircraft can be seen today as air racers. Heinkel He-162 562 mph. Arguably the fastest WW II jet fighter.
If you just look at typical cruising speed, the fastest is the Boeing 747-400ER (used only by Qantas), which cruises at Mach 0.855 (495 knots at 35,000 ft). The fastest civilian aircraft currently in operation is the Cessna Citation X, which cruises at Mach 0.92 (525 knots at 35,000 ft). Views Â· View Upvotes.